First pass at asynchronous input loading in dart2js.

sdk/lib/_internal/compiler/implementation/mirrors/dart2js_mirror.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library mirrors_dart2js;
 
 import 'dart:async';
 import 'dart:collection' show LinkedHashMap;
 
 import '../../compiler.dart' as api;
@@ skipping 208 matching lines @@
       compilationFailed = true;
     }
     diagnosticHandler(uri, begin, end, message, kind);
   }
 
   Compiler compiler = new apiimpl.Compiler(inputProvider,
                                            null,
                                            internalDiagnosticHandler,
                                            libraryRoot, packageRoot, options);
   compiler.librariesToAnalyzeWhenRun = libraries;
-  bool success = compiler.run(null);
-  if (success && !compilationFailed) {
-    return new Future<MirrorSystem>.value(new Dart2JsMirrorSystem(compiler));
-  } else {
-    return new Future<MirrorSystem>.error('Failed to create mirror system.');
-  }
+  return compiler.run(null).then((bool success) {
+    if (success && !compilationFailed) {
+      return new Dart2JsMirrorSystem(compiler);
+    } else {
+      throw 'Failed to create mirror system.';
+    }
+  });
 }
 
 //------------------------------------------------------------------------------
 // Dart2Js specific extensions of mirror interfaces
 //------------------------------------------------------------------------------
 
 abstract class Dart2JsMirror implements Mirror {
   Dart2JsMirrorSystem get mirrors;
 }
 
@@ skipping 1504 matching lines @@
  *
  * All API in this class is experimental.
  */
 class BackDoor {
   /// Return the compilation units comprising [library].
   static List<Mirror> compilationUnitsOf(Dart2JsLibraryMirror library) {
     return library._library.compilationUnits.toList().map(
         (cu) => new Dart2JsCompilationUnitMirror(cu, library)).toList();
   }
 }